The present invention relates generally to air moving apparatus, and more particularly to portable, hand-held, engine-driven blower/vacuum units used, for example, to blow away or vacuum up ground debris such as leaves, grass clippings, dust and the like.
Blower/vacuum units of this general type typically comprise a small internal combustion engine (or an electric motor) disposed within an upper portion of a hand-held housing structure having a lower end chamber in which a fan impeller is positioned and drivingly connected to the engine for rotation thereby. Rotation of the impeller draws air through an inlet opening into the lower end chamber and forces it outwardly through an elongated discharge tube, the discharged air being used to blow away the aforementioned ground debris when the unit is in its blower mode. Alternatively, a vacuum inlet tube may be secured to the inlet of the lower end chamber, and a vacuum outlet tube interconnected between the chamber outlet and a suitable vacuum bag, to suck up ground debris or the like when the unit is appropriately converted to its available vacuum mode.
While conventional blower/vacuum units of this type typically perform their air moving functions quite well, they are normally subject to two well known problems - the transmission of considerable engine vibration to the unit operator through the housing structure, and potential drive shaft and shaft bearing damage caused by impeller impact forces created by ingestion of hard objects (such as pebbles or the like) into the impeller chamber. These impact forces are particularly severe when an ingested object becomes suddenly wedged between the impeller and a portion of the housing structure which defines the impeller chamber.
A conventional approach to lessening engine vibration transmitted to the operator is to mount the operator carrying handle to the housing structure by means of resilient damping members designed to isolate the handle from engine vibration transmitted to the housing structure. While this approach lessens the engine vibration transmitted to the operator's hand it is often the case that the handle damping structure still permits an unacceptably high level of vibration to pass therethrough, thereby fatiguing the operator's hand within a relatively short period of unit operation.
In an attempt to solve the second problem--impeller impact by ingested objects--a variety of apertured guard structures have been positioned over the impeller inlet opening to prevent the ingestion of relatively heavy, ground-disposed objects such as pebbles when the unit is in its blower mode and the impeller chamber inlet is placed near the ground. However, if the guard apertures are made sufficiently small to prevent ingestion of pebbles and the like, they are likely to become readily clogged by leaves, grass clippings and the like. On the other hand, if the apertures are made larger to alleviate this clogging problem, the likelihood that pebbles and other hard objects will be ingested is increased. This ingestion problem is, of course, also present when the unit is in its vacuum mode.
In view of the foregoing, it is a primary object of the present invention to provide a portable, hand-held, engine driven blower/vacuum unit in which the above-mentioned and other problems and disadvantages associated with conventional units of this general type are eliminated or at least significantly reduced.